PRODUCT DETAILS
Competition Clutch 8.8 lb Ultra-Light Steel Flywheel for K20 Engines
Picking a K-series flywheel isn't trivial. You're deciding how your Civic Si or RSX responds every time you stab the throttle, blip for a downshift, or bang through a gear change on track. This Competition Clutch Ultra-Light Flywheel comes in at 8.8 lb, which puts it at the aggressive end of the lightweight spectrum. The engine spins up fast and drops revs just as quickly. That translates to sharper throttle response, tighter shift windows, and a more direct feel between your right foot and the rest of the drivetrain.
Competition Clutch slots this flywheel into their STU (ultra-light) line and recommends it for forced induction builds and track or rally use, paired with a Stage 3 or higher clutch kit. If you're building a boosted K20A2, prepping a dedicated track car, or running a more aggressive clutch setup, this is the flywheel Competition Clutch had in mind when they made it. It'll work on a street car too, but your clutch choice will have a bigger say in how livable the combo feels day to day.
Why 4140 Forged Steel
Most K20 lightweight flywheels land in one of two camps: aluminum or steel. Both reduce rotating mass compared to OEM, but they don't behave the same when things get hot.
This Competition Clutch flywheel uses 4140 forged steel throughout. That material soaks up and sheds heat better than aluminum, which matters when you're doing repeated hard launches, back-to-back track sessions, or running a turbo K20 that's already generating extra heat at the bellhousing. Aluminum flywheels can be lighter and may spin up a touch quicker, but they give up heat capacity and tend to transmit more gear noise into the cabin. For forced induction and track applications, the steel construction here is the right call.
- Resists heat-related warping and hot spots better than aluminum under sustained abuse
- More consistent clutch engagement lap after lap, not just on the first few passes
- Can be resurfaced at clutch replacement time rather than thrown away
- One-piece construction with the ring gear integrated, so there's no two-piece joint to worry about under load
What You'll Notice in the Car
Drop this flywheel in and the engine's character changes noticeably. It spins up faster and falls off RPM quicker between gears. The first time you try a heel-toe downshift or gas it hard out of a corner, you'll feel the difference immediately.
- Sharper, more immediate throttle response across the rev range
- Faster rev climb and drop for tighter, cleaner shifts
- Less rev hang between gears on aggressive driving
- Better timing window for heel-toe technique
How streetable the combination feels depends heavily on your clutch disc. A full-face street disc keeps things manageable for commuting and stop-and-go. Pair this with a puck-style disc and you'll get more chatter at low RPM and harder engagement. That's expected behavior from any ultra-light flywheel and aggressive clutch combo, not a defect.
Fitment
This flywheel fits K20A2, K20A3, K20Z1, and K20Z3 engines in the following applications:
- 2002-2006 Acura RSX
- 2002-2011 Honda Civic (K20-equipped variants)
Competition Clutch backs this flywheel with a 90-day limited warranty.
2002-2005 Honda Civic Si & Type R
2006-2011 Honda Civic Si & Type R
Installation Notes
Installing this flywheel requires dropping the transmission. This is a moderately involved job on a FWD K-series car. Budget a full day if you're doing it in a home garage with basic tools, less if you've done a clutch job on a Civic or RSX before.
You'll need a flywheel holding tool to keep the flywheel from spinning while torquing the crank bolts. The flywheel bolts should be torqued to Honda's spec for the K20 application. Use new flywheel bolts if yours have been removed before, as these are torque-to-yield fasteners on many applications.
Competition Clutch recommends pairing this ultra-light flywheel with a Stage 3 or higher clutch kit. If you're unsure which clutch stage suits your build, check Competition Clutch's clutch kit selector or contact their tech line before purchasing.
The friction surface can be resurfaced by a machine shop at clutch replacement if needed. Inspect it for heat cracks or scoring before resurfacing rather than assuming it's serviceable.
Technical Details
Weight: 8.8 lb
Material: 4140 forged steel
Construction: One-piece solid flywheel with integrated ring gear. Not a two-piece assembly.
Resurfaceable: Yes. You can have this resurfaced at clutch replacement time the same way you'd treat an OEM flywheel.
Flywheel type: Solid
Recommended use: Competition Clutch designates this as an STU (ultra-light) flywheel and recommends it for forced induction and track or rally racing applications, paired with Stage 3 or higher clutch kits.
Compatible engines: K20A2, K20A3, K20Z1, K20Z3
Transmission: Manual
Drive type: FWD
Warranty: 90-day limited warranty from Competition Clutch
For reference, Competition Clutch also offers an ST (lightweight) flywheel for K20A2/A3/Z1/Z3 applications at a heavier weight, which is better suited to Stage 1-2 clutch setups and naturally aspirated street builds. If you're running a stock or mildly modified street car without boost, that version is worth considering before committing to the ultra-light.
- 1x Competition Clutch Ultra-Light Flywheel (8.8 lb, 4140 forged steel)
Clutch kit, pressure plate, and hardware are not included. Verify clutch disc diameter and clutch kit stage compatibility with Competition Clutch's fitment guide before ordering.